Oh dear, while the answer the masses have selected is correct, the reasoning is flawed. There is no matter of "balancing books." Rather, Congress's ability to change its pay is regulated by the twenty seventh amendment to the Constitution. The amendment states that "No law, varying the compensation for the services of the Senators and Representatives, shall take effect, until an election of Representatives shall have intervened." That means that the increase or decrease wouldn't take effect until the start of congressional term. Answering your question, no - it cannot take effect immediately.